Spring may receive most of the gardening attention, but autumn offers its own planting season.
Cooling temperatures reduce transplant stress. Rainfall often becomes more dependable. Weed growth slows, and the soil remains warm enough for roots to become established after the air has turned comfortable.
For gardeners in coastal New England, fall can be an excellent time to establish hardy perennial herbs, sow a final crop of cool-season annuals and plant garlic for the following summer.
The secret is timing. Fall planting should give perennial roots time to settle without encouraging excessive tender growth immediately before winter.
Hardy Perennial Herbs
Established plants of these herbs can generally tolerate a Cape Cod winter when planted in well-drained soil:
Chives
Garlic chives
Thyme
Oregano
Sage
Lemon balm
Mint
Sorrel
Salad burnet
Lovage
Winter savory
Illinois Extension identifies chives, lemon balm, oregano, sage and thyme as useful perennial culinary herbs. Illinois Extension
Plant healthy transplants approximately four to six weeks before the ground normally freezes. The objective is root establishment—not a flush of soft new foliage.
Water deeply after planting and continue watering when rainfall is insufficient. Roots can dry even when the air feels cool.
Drainage Matters More in Winter
Many Mediterranean herbs tolerate cold better than they tolerate cold, saturated soil.
Thyme, oregano, sage and lavender need excellent drainage. Raised beds, gravelly berms and locations that shed winter water are safer than low pockets.
Do not enrich their planting holes with heavy amounts of manure or rich fertilizer. Excess nitrogen can produce tender growth that is less prepared for winter.
Lavender deserves particular caution. A mature, established plant may overwinter well in a favorable Cape Cod location, but a small fall transplant can be vulnerable to winter wetness and frost heaving. Spring remains the safer season for establishing an important lavender planting.
Mint and Lemon Balm Need Boundaries
Mint and lemon balm can spread aggressively through roots or seed.
Plant them in large containers, contained beds or locations where their expansion will not threaten more restrained herbs. Do not confuse hardiness with good manners.
Fall is also a useful time to divide established clumps of mint, lemon balm, chives and oregano. Replant the strongest outer portions and compost tired or woody centers.
Cool-Season Annual Herbs
Several annual and biennial herbs prefer cool conditions:
Cilantro
Chervil
Dill
Parsley
Cilantro is especially valuable as a fall crop because summer heat causes it to flower rapidly. Sow small amounts in succession rather than planting the entire packet at once.
Chervil also appreciates cool weather and some protection from strong afternoon sun.
Dill can produce tender foliage before heavy frost, although late sowings may not have time to form mature seed heads.
Parsley tolerates considerable cold and may continue producing well into fall. In protected locations, it sometimes survives winter and resumes growth in spring before completing its biennial life cycle.
A low tunnel, cold frame or floating row cover can extend the harvest, but the covering should not crush the plants under snow.
Garlic: The Great Fall Tradition
Garlic is among the most dependable fall plantings.
Separate healthy bulbs into individual cloves shortly before planting. Set each clove with its pointed end upward. Allow it to establish roots before winter, then protect the bed with clean straw or another loose mulch after the soil cools.
Illinois Extension recommends planting garlic in fall, usually around one or two weeks after the first killing frost. Illinois Extension
Garlic planted in autumn generally produces larger, better-developed bulbs than garlic planted late in spring.
Herbs Better Left Until Spring
Do not treat every herb as a fall candidate.
Wait until warm weather for:
Basil
Lemon verbena
Lemongrass
Stevia
Pineapple sage
Tender marjoram
Tender rosemary
Rosemary can be overwintered indoors, but it often struggles with dry household air, insufficient light and overwatering. A cool, bright location generally suits it better than a hot windowsill.
Basil should be harvested before frost. Even a short exposure to cold can blacken its foliage.
Preparing the Fall Herb Bed
A good fall planting does not require a complicated fertilizer program.
Remove perennial weeds.
Loosen compacted soil without pulverizing it.
Incorporate a moderate amount of mature compost if needed.
Correct pH only according to a soil test.
Plant at the same depth the herb occupied in its container.
Water thoroughly.
Label each plant before winter removes its visible growth.
Apply winter mulch after the ground becomes cold—not while it remains warm.
Mulching too early can shelter rodents and delay dormancy. Keep mulch away from crowns that are vulnerable to rot.
Planting for the Spring You Cannot Yet See
Fall planting is an act of confidence.
Garlic disappears beneath its mulch. Chives retreat into the earth. Thyme seems to stop moving. The herb garden becomes quiet.
Below the surface, however, roots are settling into place. When spring arrives, these plants will not be waiting in nursery pots. They will already belong to the garden.
Until next time...
I am...
Phil Wilson...
and Here’s to sharing our herbal life-style with you!